you need to remove the tank and the whole airbox will come out together with the throttle bodies, you need to split the airbox then and only then you will be able to unscrew those screws, I don't remember the exact steps nor do I have the pictures on hand from when I was changing the velocity stacks from EU to the US model, but it's not that complicated if you are careful, you will even be able to reuse the "one time use" connectors on the tank if you are careful enough